Disposable diaper

ABSTRACT

The present invention provides a disposable diaper in which a discharged stool does not easily directly contact with the skin of a wearer of the diaper. A disposable diaper  1  includes an absorber  22 , a top sheet  18  disposed to cover an upper surface of the absorber  22  and at least partially formed of a liquid permeable material, and a back sheet  20  disposed to cover a lower surface of the absorber  22  and formed of a liquid impermeable material. The disposable diaper  1  further includes a skin contact sheet  24  disposed above the top sheet  18  and formed with a stool passing opening  28 , which is an opening capable of passing a stool therethrough, and to the both sides of the skin contact sheet  24 , at least a pair of standing gathers  26   a  and  26   b  which are leakage prevention walls capable of three-dimensionally standing is formed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disposable diaper including anabsorber, a top sheet, and a back sheet. The disposable diaper furtherincludes a skin contact sheet which is disposed above the top sheet andformed with an opening capable of passing a stool therethrough.

2. Description of the Related Art

In recent years, as a diaper for an infant or an elder or disabledperson, there has been a widely used a disposable diaper which includesan absorber, a top sheet disposed to cover the upper surface of theabsorber and at least partially formed of a liquid permeable material,and a back sheet disposed to cover the lower surface of the absorber andformed of a liquid impermeable material. This disposable diaper is usedin such a manner that a surface of the top sheet is applied to contactthe skin of a wearer of the disposable diaper. Thereby, the urinedischarged by the wearer penetrates through the top sheet and isabsorbed and retained by the absorber. Further, the back sheet havinggood leakage preventing performance prevents the leakage of theexcrement to the outside of the diaper.

In the disposable diaper of the above-described structure, however, theurine penetrates through the top sheet but most of the stool does notpenetrate through the top sheet and thus remains thereon. The stoolremaining on the top sheet adheres to the crotch or the buttocks of thewearer. This requires a troublesome wiping work which increases theburden of child rearing or nursing care, and also causes skin trouble tothe wearer. Such phenomenon becomes more prominent when the stooldischarged by the wearer is an unformed stool.

In view of this, another type of disposable diapers has been proposed inwhich another sheet member (hereinafter referred to as a “skin contactsheet” in the present specification) is disposed above the top sheet(see Paragraph 0010 and FIG. 2 of Japanese Registered Utility Model No.2559050, and Paragraph 0020 and FIG. 1 of Japanese Unexamined PatentApplication Publication No. 2002-11044, for example). These disposablediapers are structured such that the skin contact sheet is formed withan opening capable of passing the stool therethrough (i.e., a stoolpassing opening) for causing the stool discharged by the wearer to dropon the top sheet through the stool passing opening.

According to the above-described disposable diaper, the skin contactsheet first contacts the skin of the wearer. Thus, the top sheetdisposed under the skin contact sheet does not easily come into directcontact with the skin of the wearer. That is, the skin of the wearer isseparated from the top sheet. This also means that a shielding layer,i.e., the skin contact sheet intervenes between the top sheet and theskin of the wearer. Therefore, even if the stool remains on the topsheet, the effect of substantially decreasing the chance of directcontact of the stool with the skin of the wearer can be expected.

However, in the disposable diaper having the skin contact sheet, ascompared with known disposable diapers, leakage from leg-surroundingopenings and the like of the diaper (i.e., the so-called sidewardleakage) easily occurs. That is, the disposable diaper is notsatisfactory enough in the prevention of the sideward leakage of urine,and thus is still open to improvement.

SUMMARY OF THE INVENTION

As described above, a disposable diaper in which the discharged stooldoes not easily contact with the skin of the wearer and capable ofeffectively preventing the sideward leakage of urine has not yet beendisclosed so far, and thus has been longed for. In view of theconventional techniques as described above, it is an object of thepresent invention to provide a disposable diaper in which the dischargedstool does not easily contact with the skin of the wearer and capable ofeffectively preventing the sideward leakage of urine.

The present inventors conducted a keen examination to improve theabove-described conventional techniques and obtained a finding that, inthe disposable diaper having the skin contact sheet, urine is sometimesdischarged on the skin contact sheet. In such a case, because the urinediffuses down the skin contact sheet, the sideward leakage of the urinetends to occur. Then, to solve the above-described disadvantages, inaddition to providing the skin contact sheet, the present inventors hasbeen made with the idea of forming at least a pair of standing gathersto both sides of the skin contact sheet. Specifically, the presentinvention provides the following disposable diaper.

A disposable diaper according to a first aspect of the present inventionincludes an absorber, a top sheet disposed to cover an upper surface ofthe absorber and at least partially formed of a liquid permeablematerial, and a back sheet disposed to cover a lower surface of theabsorber and formed of a liquid impermeable material. The disposablediaper further includes a skin contact sheet disposed above the topsheet and formed with a stool passing opening, which is an openingcapable of passing a stool therethrough, and to the both sides of theskin contact sheet, at least a pair of standing gathers which areleakage prevention walls capable of three-dimensionally standing isformed.

According to a second aspect of the present invention, in the disposablediaper according to the first aspect of the present invention, thestanding gathers are formed with folded parts of side edges of the skincontact sheet and integrally formed with the skin contact sheet.

According to a third aspect of the present invention, in the disposablediaper according to the first or second aspect of the present invention,the standing gathers are formed along both side edges of the skincontact sheet.

According to a fourth aspect of the present invention, in the disposablediaper according to either one of the first to third aspects of thepresent invention, the standing gathers are formed that upper end edgesof the standing gathers are disposed to positions higher than a surfaceof the skin contact sheet.

According to a fifth aspect of the present invention, in the disposablediaper according to either one of the first to fourth aspects of thepresent invention, the standing gathers' lower end edges are disposed onthe surface of the skin contact sheet.

In the disposable diaper according to the present invention, thedischarged stool does not easily directly contact with the skin of thewearer and the disposable diaper is capable of effectively preventingthe sideward leakage of urine. That is, the disposable diaper accordingto the present invention is excellent in preventing the disadvantage(sideward leakage of urine) due to the provision of the skin contactsheet while retaining the advantage of the provision of the skin contactsheet. Incidentally, the word “standing gather(s)” may be expressed as“barrier cuff”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating one embodiment ofthe disposable diaper according to the present invention, as viewed fromthe front side of the diaper.

FIG. 2 is a plan view illustrating the one embodiment of the disposablediaper according to the present invention, as viewed from the side ofthe absorbent member of the disposable diaper when the diaper shown inFIG. 1 is unfolded.

FIG. 3 is a schematic cross-sectional view illustrating the oneembodiment of the disposable diaper according to the present invention,as cut along the X-X′ line in the disposable diaper shown in FIG. 2.

FIG. 4 is a schematic cross-sectional view illustrating the anotherembodiment of the disposable diaper according to the present invention,as cut the disposable diaper according to the present invention at thepart of the stool passing opening in the width direction.

FIG. 5 is a schematic cross-sectional view illustrating still anotherembodiment of the disposable diaper according to the present invention,as cut the disposable diaper according to the present invention at thepart of the stool passing opening in the width direction.

FIG. 6 is a schematic cross-sectional view illustrating still yetanother embodiment of the disposable diaper according to the presentinvention, as cut the disposable diaper according to the presentinvention at the part of the stool passing opening in the widthdirection.

FIG. 7 is a schematic cross-sectional view illustrating still yetanother embodiment of the disposable diaper according to the presentinvention, as cut the disposable diaper according to the presentinvention at the part of the stool passing opening in the widthdirection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Specific description will now be made of preferred embodiments of thedisposable diaper according to the present invention, taking atwo-piece-type and pants-type diaper as an example. The presentinvention, however, widely includes disposable diapers which haveparticular features of the invention, and thus is not limited to thefollowing embodiments. For drawing convenience, leg-surroundingstretchable members are eliminated from FIG. 3 to FIG. 7.

In the present specification, the “pants-type diaper” refers to a diaperpreformed into a pants shape, as in the case of a disposable diaper 1illustrated in FIGS. 1 and 2, in which corresponding side edges of afront body part 2 and a back body part 6 (i.e., side edges 2 a and 6 aand side edges 2 b and 6 b) are joined together to form joining parts 8,a waist-surrounding opening 10, and a pair of leg-surrounding openings12 a and 12 b. Further, the “two-piece-type diaper” refers to a type ofdiaper which includes an absorbent member 14 having a function ofabsorbing and retaining the excrement of a wearer of the diaper (i.e.,an absorbing and retaining function) and an exterior covering member 16having a function of covering the body of the wearer (i.e., a fittingfunction), and in which the absorbent member 14 is disposed on theinside of the exterior covering member 16. As illustrated in FIG. 3, theabsorbent member 14 is a member including, as component parts thereof,an absorber 22, a top sheet 18, and a back sheet 20.

Further, in the present specification, the “front body part,” refers toa part covering the ventral part (i.e., the front side of the body) of awearer when the diaper is applied to the wearer, the “crotch part,”refers to a part covering the crotch of a wearer when the diaper isapplied to the wearer, and the “back body part” refers to a partcovering the dorsal part (i.e., the back side of the body) of a wearerwhen the diaper is applied to the wearer, respectively.

[1] The structure of the disposable diaper according to the presentinvention: As in the case of the disposable diaper 1 illustrated inFIGS. 1 to 3, the disposable diaper according to the present inventionis a disposable diaper including the absorber 22, the top sheet 18, andthe back sheet 20. The disposable diaper further includes a skin contactsheet 24 which is disposed above the top sheet 18 and is formed with anopening capable of passing the stool therethrough (i.e., a stool passingopening 28 a). To the both sides of the skin contact sheet 24, at leasta pair of standing gathers 26 (26 a and 26 b) which are leakageprevention walls structured to stand three-dimensionally is formed.

[1-1] The skin contact sheet: The skin contact sheet is a member forseparating the skin of the wearer from the top sheet, and is asheet-shaped member disposed above the top sheet and formed with anopening capable of passing the stool therethrough (i.e., a stool passingopening). With the provision of the skin contact sheet, the skin of thewearer first contacts the skin contact sheet, and thus the top sheetdisposed under the skin contact sheet does not easily come into directcontact with the skin of the wearer. That is, the skin of the wearer isseparated from the top sheet. This also means that a shielding layer,i.e., the skin contact sheet intervenes between the top sheet and theskin of the wearer. Therefore, even if the stool remains on the topsheet, the effect of substantially decreasing the chance of directcontact of the stool with the skin of the wearer is obtained.

As the material forming the skin contact sheet, for example, a nonwovenfabric, a mesh sheet, a film, or the like made of such a resin aspolyethylene, polypropylene, and polyester can be used. In particular,it is preferable to use the nonwoven fabric for the good texture againstthe skin. The above-described materials may be liquid permeable, liquidimpermeable, or water repellent. It is preferable, however, that theabove-described materials are water repellent materials (e.g., a waterrepellent nonwoven fabric) for the ability to maintain a dry texture(i.e., dryness) even after a long time wearing.

The skin contact sheet of the disposable diaper according to the presentinvention needs to be formed with the opening capable of passingtherethrough the stool discharged by the wearer (i.e., the stool passingopening). With this structure, the stool discharged by the wearer dropson the top sheet through the skin contact sheet, and thus the chance ofdirect contact of the stool with the skin of the wearer can besubstantially decreased.

There is no particular restriction on the shape of the stool passingopening, as long as the shape allows the passage of the stool. That is,the “opening” capable of passing the stool therethrough includes theso-called opening (i.e., a hole) such as a circular opening, an ovalopening, and a rhombic opening, and also includes a slit such as astraight-line slit, a cross-shape slit, and a star-shape slit formed bycrossing three or more slits. Specifically, the oval opening, or thestar-shape slit in which an anteroposterior direction (longitudinaldirection) of the diaper is a long axis direction is preferable. Theoval opening has an advantage that the stool can easily pass through theopening of the skin contact sheet, and the star-shape slit has anadvantage of effectively preventing that the stool once passed throughthe opening of the skin contact sheet and dropped onto the top sheetexposes again from the opening of the skin contact sheet and contaminatethe buttocks of the wearer. For example, the disposable diaper 1illustrated in FIG. 2 is an example of a disposable diaper on which anoval opening whose anteroposterior direction is the long axis directionis formed to the part corresponding to a crotch part 4 of the skincontact sheet 24 as the stool passing opening 28 a. Sizes of the holeand slit can be appropriately decided in consideration of the functionof “passing the stool”.

The skin contact sheet may be formed with a urine passing opening to aregion toward the front body side from the stool passing opening. Thatis, it is preferable that the skin contact sheet is formed with thestool passing opening and the urine passing opening, as the openings.

With the formation of the urine passing opening as described above, itis possible to cause the urine discharged by the wearer to securely flowinto the inside of the skin contact sheet through the opening. Thereby,it is possible to effectively prevent the urine from diffusing down theskin contact sheet and leaking sideward from the leg-surroundingopenings and the like of the diaper. For instance, the disposable diaper1 illustrated in FIG. 2 is an example in which, in addition to the stoolpassing opening 28 a of the oval shape, a urine passing opening 28 b ofan oval shape is further formed on the skin contact sheet 24 as theopening 28. In this example, the stool passing opening 28 a is formed ata portion corresponding to the crotch part 4 of the disposable diaper 1,and the urine passing opening 28 b is formed at a portion toward thefront body part 2 from the stool passing opening 28 a.

In the case in which two openings (i.e., the stool passing opening andthe urine passing opening) are formed as in the above-described case, itis preferable to provide a separation wall for dividing the spacebetween the skin contact sheet and the top sheet into a spacecommunicating with the stool passing opening and a space communicatingwith the urine passing opening.

If the urine and the stool are mixed, ammonia is generated andalkalinizes the surrounding environment. Then, an enzyme included in thestool is strongly activated in an alkaline atmosphere, and the enzymeand ammonia inflame a weakened part of the skin. Thereby, the diaperrash occurs. This mechanism is reported by Kazuya Yamamoto in HifuRinsho (Clinical Dermatology) 1998, vol. 30, pp 949-956. With theprovision of the above-described separation wall, the urine dischargedby the wearer can be absorbed and retained separately from the stool. Asa result, the urine and the stool are not easily mixed, and the diaperrash can be effectively prevented.

It is preferable that a stretchable member (i.e., an opening stretchablemember) is placed around the outer periphery of the opening. With theprovision of the opening stretchable member, the skin contact sheet isapplied with tension and thus becomes elastic. This contributes to anadvantage that the skin contact sheet can be prevented from beingcrushed and sinking toward the top sheet, and that the skin contactsheet can easily come into contact with the skin of the wearer. Further,with the provision of the opening stretchable member, it is possible togenerate force for causing the skin contact sheet to contract andcausing the top sheet, the absorber, and the back sheet to bend towardthe downside (i.e., toward the exterior covering member). Therefore, theskin contact sheet can be kept spaced from the top sheet, and the skincontact sheet and the top sheet can be definitely separated from eachother.

As the material for the opening stretchable member, stretchablematerials used in conventional disposable diapers can be preferablyused. Specifically, the material may be a rubber thread or a flat rubberstring made of a natural rubber or a synthetic rubber (e.g., urethanerubber), a stretchable net, a stretchable film, stretchable foam (e.g.,urethane foam), or the like.

There is no particular restriction on the arrangement pattern of theopening stretchable member, as long as the pattern allows the exertionof the above-described effects. To definitely apply the stretching forceto the opening, however, it is preferable that the opening stretchablemember is arranged in such a pattern to surround the peripheral rim ofthe opening. For example, it is preferable to arrange the openingstretchable member in such a pattern as a circular pattern, an ovalpattern, or a rhombic pattern to surround the peripheral rim of theopening.

In another preferable embodiment, two opening stretchable members areused as the opening stretchable members and arranged in such a patternto cross at least one point anterior or posterior to the opening so asto surround a part of the peripheral rim of the opening. With theopening stretchable members arranged in such a pattern, the openingstretchable members can be continuously arranged in the anteroposteriordirection of the diaper. This is preferable in view of the advantagethat the continuous manufacture of disposable diapers can be easilyperformed.

For example, the disposable diaper 1 illustrated in FIG. 2 is an examplein which two opening stretchable members 30 a and 30 b are used as theopening stretchable members 30 and arranged in such a pattern to crossat a point P between the stool passing opening 28 a and the urinepassing opening 28 b so as to surround a part of the peripheral rim ofeach of the stool passing opening 28 a and the urine passing opening 28b. With the opening stretchable members 30 a and 30 b arranged in such apattern, it is possible to easily manufacture an absorbent membercontinuum in which the absorbent member 14 is continuously arranged inthe longitudinal direction.

Further, in the disposable diaper 1 illustrated in FIG. 2, the openingstretchable members 30 a and 30 b are arranged to cross at the center ofthe crotch part 4. With this arrangement, the stretching force in thewidth direction (i.e., the sideward direction of the diaper) can beapplied more at the crotch part 4 (i.e., the proximity of the point P)than at the front body part 2 or the back body part 6 of the diaper.Therefore, there is an effect of making the skin of the wearer come intocloser contact with a portion of the skin contact sheet 24 between thestool passing opening 28 a and the urine passing opening 28 b, whichtends to sag with relative ease. Furthermore, in the disposable diaper 1illustrated in FIG. 2, the opening stretchable members 30 a and 30 b donot cross at other points than the center point P of the crotch part 4.Thus, the opening stretchable members 30 a and 30 b are arranged in sucha pattern that a part of the peripheral rim of the stool passing opening28 a at the side of the back body part 6 and a part of the peripheralrim of the urine passing opening 28 b at the side of the front body part2 are open. With this arrangement, portions of the skin contact sheet 24at the sides of front body part 2 and the back body part 6 do not comeinto excessively close contact with the skin of the wearer, and thus thebreathability can be ensured. Accordingly, perspiration due to thecontact of the skin contact sheet is suppressed, and the stuffiness andthe skin trouble attributable to the sweat can be effectively prevented.

The opening stretchable member as described above is fixed to the skincontact sheet with an adhesive agent or another medium. The method offixing the opening stretchable member may be bonding with a hot-meltadhesive agent or another adhesive agent of high fluidity, or weldingwith heat or ultrasound such as heat-sealing, for example.

To apply sufficient stretching force to the opening, it is preferable tofix the opening stretchable member with the opening stretchable memberstretched. For example, if the opening stretchable member is a naturalrubber or a synthetic rubber, it is preferable to fix the openingstretchable member with the opening stretchable member stretched by 100to 400%, and more preferably by 200 to 300%. With the openingstretchable member fixed with the stretching rate of the above range, itis possible to apply the sufficient stretching force to the opening andto prevent the opening from unnecessarily contracting.

There is no particular restriction on the method of arranging theopening stretchable member. However, as in the case of the disposablediaper 1 illustrated in FIG. 3, for example, it is preferable to formthe skin contact sheet 24 by pasting together two sheet members (i.e.,an upper sheet 24 a and a liner sheet 24 b), and to place the openingstretchable members 30 a and 30 b to be sandwiched between the uppersheet 24 a and the liner sheet 24 b. The use of this arrangement methodis preferable in that the stretching force can be applied to the skincontact sheet by the minimum necessary stretchable members.

When the above-described structure is employed, it is enough if theportion of the skin contact sheet where the opening stretchable membersare placed is formed with two sheet members, and it is not necessarythat the whole of the skin contact sheet is formed with the two sheetmembers. For example, in a disposable diaper 90 illustrated in FIG. 7, aportion where the opening stretchable members 30 a and 30 b are placedis formed with the two sheet members (i.e., the upper sheet 24 a and theliner sheet 24 b) and other parts are parts are formed with one sheetmember (the upper sheet 24 a).

With the above-described structure, a portion standing from a standingline 46 of the skin contact sheet 24 is formed with only one sheetmember (i.e., the upper sheet 24 a), as compared with the case in whichthe portion is formed with two sheet members, the portion standing fromthe standing line 46 becomes soft and flexible. Accordingly, there areadvantages that the skin contact sheet 24 easily stands to fit the shapeof the skin of the wearer (i.e., the portion of the crotch), easily comeinto close contact, and good fittedness can be obtained. Therefore,original effect of the skin contact sheet significantly contributes. Thedisposable diaper 90 illustrated in FIG. 7 is an example of a diaperformed such that the liner sheet 24 b is formed to have narrow width andwith the upper sheet 24 a which has a wide width protruding from theliner sheet 24 b which has the narrow width, standing gathers 26 a and26 b are formed. On the contrary, similar effect can be obtained even ifthe upper sheet is formed to have a narrow width and with a liner sheetwhich has a wide width protruding from the upper sheet having the narrowwidth, the standing gathers are formed.

The method of fixing the skin contact sheet includes, for example, (1) amethod of fixing the skin contact sheet 24 such that the skin contactsheet 24 is inserted in portions where sheet members 32 a and 32 b,which form standing gathers 26 a and 26 b, respectively, are pasted withthe top sheet 18 (or the back sheet 20), as in the case of thedisposable diaper 1 illustrated in FIG. 3, and (2) a method of fixingthe skin contact sheet 24 to portions on the inside surfaces of thestanding gathers 26 a and 26 b between upper end edges 34 and loweredges (i.e., standing lines 38) of the standing gathers 26 a and 26 b,as in the case of a disposable diaper 60 illustrated in FIG. 4.

Alternatively, the skin contact sheet may be fixed in an inside regionencompassed by the pair of the standing gathers without being in contactwith the standing gathers. For example, there is (3) a method of fixingthe skin contact sheet 24 in portions where the top sheet 18 and theback sheet 20 of the absorbent member 14 are pasted together (i.e.,so-called flap portions) within the region encompassed by the standinggathers 26 a and 26 b as in the case of a disposable diaper 70illustrated in FIG. 5, and (4) a method of fixing the skin contact sheet24 in portions corresponding to an upper portion of the absorber 22 ofthe top sheet 18 which constitutes the absorbent member 14 within theregion encompassed by the standing gathers 26 a and 26 b as in the caseof a disposable diaper 80 illustrated in FIG. 6.

Further, there is (5) a method of fixing the skin contact sheet 24, in acase in which the absorbent member 14 is formed so that the back sheet20 protrudes from the lower side of the top sheet 18, within the regionencompassed by the standing gathers 26 a and 26 b, the skin contactsheet 24 can be fixed on both of the top sheet 18 and the back sheet 20of the absorbent member 14 as in the case of the disposable diaper 90illustrated in FIG. 7. The method (1) is preferable among the abovemethods (1) to (5) in that the method is highly effective in making theskin contact sheet in close contact with the skin of the wearer.

[1-2] The standing gathers: The standing gathers are members forpreventing the sideward leakage of the urine discharged by the wearer,and are leakage preventing walls structured to standthree-dimensionally. With the provision of the standing gathers, even ifthe urine is discharged on the skin contact sheet and diffuses down theskin contact sheet, the standing gathers function as breakwaters, andthe leakage from the leg-surrounding openings and the like of the diaper(i.e., the so-called sideward leakage) can be effectively prevented.

The standing gather can employ a similar structure to the structure usedin the conventional disposable diaper and other absorbent products. Forexample, by providing a stretchable member (i.e., a standing gatherstretchable member) on a part of a sheet member, a gather (i.e., folds)formed on the sheet member by the standing gather stretchable member canbe preferably used.

As the material forming the standing gathers, it is preferable to usewater-repellent material in a view of increasing the leakage preventingperformance of the standing gathers. As the water-repellent material,nonwoven fabrics such as a spunbond, or a card-emboss can be used,however, for the reason of high anti-hydraulic pressure, it ispreferable to use nonwoven fabrics such as a SMS(spunbonded/meltblown/spunbonded) or a SMMS(spunbonded/meltblown/meltblown/spunbonded).

The standing gathers can be formed by folding back the top sheet or backsheet of the absorbent member 14 or the skin contact sheet. For example,in the disposable diaper 90 illustrated in FIG. 7, a pair of thestanding gathers 26 a and 26 b is formed by folding back the both sideedges of the skin contact sheet 24. More specifically, the disposablediaper 90 is an example that the standing gathers are formed with thefolded edges of the skin contact sheet, and the standing gathers areintegrally formed with the skin contact sheet. However, it is preferableto form the standing gathers by pasting sheet members which aredifferent from the top sheet, the back sheet, and the skin contactsheet. For example, as in the case of the disposable diaper 1illustrated in FIGS. 2 and 3, a pair of the standing gathers 26 a and 26b are formed by pasting sheet members 32 a and 32 b which are differentfrom the top sheet 18 or the back sheet 20 to portions of both edges ofthe absorbent member 14.

As the standing gather stretchable member, similar stretchable member tothe above-described opening stretchable member can be used. For onestanding gather, a single standing gather stretchable member or aplurality of standing gather stretchable members can be arranged.Further, there is no limitation on the position of the arrangement. Forexample, the standing gather stretchable member can be arranged in theproximity of the lower end edge (i.e., the standing line) of thestanding gather or between the upper end edge and the lower end edge(i.e., the standing line) of the standing gather. However, it ispreferable to arrange the standing gather in the proximity of the upperend edge of the standing gather.

The disposable diaper 1 illustrated in FIGS. 2 and 3 is an example inwhich a standing gather stretchable member 36 is arranged in theproximity of the upper end edges of the standing gathers 26 a and 26 b.In this example, an edge portion of each of the sheet members 32 a and32 b (i.e., an edge portion corresponding to the upper end edge 34 ofeach of the standing gather 26 a and 26 b) is folded, and the foldedportion tucks therein the two standing gather stretchable members 36 aand 36 b or the two standing gather stretchable members 36 c and 36 d.

With respect to the height of the standing gather (the length from thelower end edge to the upper end edge), it is preferable that the heightis to be between 5 mm and 80 mm, and it is more preferable that theheight is to be between 10 m and 40 mm. By making the height of thestanding gather to be 5 mm or more, sufficient leakage prevention effectcan be ensured, and in addition, by making the height to be 80 mm orless, it is possible to prevent a disadvantage that the absorptioneffect is inhibited because the standing gather covers a surface of theskin contact sheet or the top sheet.

The standing gathers include types, for example, (1) an inside-inclinedgather which inclines toward the inside of the diaper, (2) anoutside-inclined gather which inclines toward the outside of the diaper,and (3) a standing gather to which a bent part or a folded part isformed at a part in the height direction (a C-folding gather, aZ-folding gather, etc.). Among the above gathers, the inside-inclinedgather is preferable. For example, the disposable diaper 1 illustratedin FIGS. 2 and 3 is an example of the inside-inclined gather in whichthe standing gathers 26 a and 26 b are inclined toward the inside.

In order to prevent the side leakage of urine, it is preferable that thestanding gathers are formed to the both sides of the skin contact sheet.It is more preferable that the standing gathers are formed along theboth side edge parts of the skin contact sheet. By the structure, evenif the urine is discharged on the skin contact sheet and diffuses downthe skin contact sheet, the standing gathers function as breakwaters,and the sideward leakage from the leg-surrounding openings can beeffectively prevented.

For example, the disposable diaper 1 illustrated in FIGS. 2 and 3 is anexample in which the skin contact sheets 24 are disposed onto both sideedges of the absorbent member 14 and the standing gathers 26 a and 26 bare formed on the both side edges of the skin contact sheets 24, thatis, along the both side edges of the absorbent member 14. The disposablediaper 1 illustrated in FIGS. 2 and 3 is an example in which thestanding gathers 26 a and 26 b are formed over the entire of the bothside edges, however, in order to prevent the sideward leakage of urine,the standing gathers 26 a and 26 b may be disposed at least to theportion corresponding to the crotch part of the disposable diaper.

As in a case of the disposable diaper 90 illustrated in FIG. 7, if theskin contact sheets 24 and the standing gathers 26 a and 26 b areintegrally formed respectively, the disposable diaper in which thestanding gathers 26 a and 26 b are formed along the both standing lines46 of the skin contact sheets 24 has similar effect as “the disposablediaper in which the standing gathers are formed along the both sideedges of the skin contact sheet”, thus, included in the scope of thepresent invention. Because original part where functions as the skincontact sheet is the part upper than the standing line, in the case inwhich the skin contact sheet and the standing gather are integrallyformed, the standing line of the skin contact sheet can be considered asthe side edge of the skin contact sheet. That is, also in suchstructured disposable diaper, even if the urine is discharged on theskin contact sheet and diffuses down the skin contact sheet, thestanding gathers function as breakwaters, and the sideward leakage fromthe leg-surrounding openings can be effectively prevented.

It is preferable to form the standing gather into such a structure thatthe upper end edge of the standing gather is disposed to a positionhigher than the surface of the skin contact sheet. With the structure,even if the urine is discharged on the skin contact sheet and diffusesdown the skin contact sheet, it can be prevented that the urine leaksout over the standing gather.

The method of disposing the upper end edge of the standing gather to aposition higher than the surface of the skin contact sheet includes amethod of disposing the lower end edge of the standing gather onto thesurface of the skin contact sheet. That is, in the disposable diaperaccording to the present invention, it is preferable to dispose thelower end edge of the standing gather onto the surface of the skincontact sheet. With the structure, the upper end edge of the standinggather is definitely disposed to the position higher than the surface ofthe skin contact sheet. Then, by adequately adjusting the height of thestanding gather depending on the surface height of the skin contactsheet, it is possible to definitely prevent that the urine leaks outover the standing gather.

For example, the disposable diaper 1 illustrated in FIG. 3 is an examplein which the skin contact sheets 24 are fixed to the pasted part to besandwiched between the standing gathers 26 a and 26 b and the top sheet18 respectively so that the lower end edges of the standing gathers 26 aand 26 b are disposed on the surface of the skin contact sheet 24 andthe upper end edges 34 are disposed to the position higher than thesurface of the skin contact sheet 24. In the present specification, the“lower end edge of the standing gather” refers to the fixed end of thestanding gathers 26 a and 26 b, that is, the part of the standing line38 as illustrated in FIG. 3.

As in a case of the disposable diaper 90 illustrated in FIG. 7, themethod of forming the standing gathers 26 a and 26 b by folding the sideend side of the skin contact sheet 24 has similar effect to “the methodof disposing the lower end edge of the standing gather onto the surfaceof the skin contact sheet”, thus included in the scope of the presentinvention. Because as in the case of the disposable diaper 90illustrated in FIG. 7, if the skin contact sheet 24 and the standinggathers 26 a and 26 b are integrally formed, it is possible to considerthat the lower end edges of the standing gathers 26 a and 26 b (standinglines 38) and the surface of the skin contact sheet 24 are continuouslyformed respectively. That is, also in such structured disposable diaper,by adequately adjusting the height of the standing gather depending onthe surface height of the skin contact sheet, it is possible todefinitely prevent that the urine leaks out over the standing gather.

In the disposable diaper according to the present invention, at least apair of standing gathers should be formed, however, more than one pairof the standing gathers may be formed.

[1-3] The absorber: The absorber is a member for absorbing and retainingthe urine of the wearer. The absorber is made of an absorbent materialdue to the need to absorb and retain the urine and the body fluid of thewearer.

The absorbent material forming the absorber includes conventionallyknown absorbent materials usually used in the disposable diaper andother absorbent products, such as fluff pulp, super absorbent polymer(hereinafter refereed to as SAP), and a hydrophilic sheet, for example.It is preferable to use wood pulp or non-wood pulp fibrillated into flocas the fluff pulp, to use sodium polyacrylate as the SAP, and to usetissue, an absorbent paper, or a hydrophilicized nonwoven fabric as thehydrophilic sheet.

Each of these absorbent materials is usually used in the form of asingle-layer mat or a multiple-layer mat. In such a case, a single typeof the above absorbent materials may be independently used, or two ormore types of the absorbent materials may be used in combination. Inparticular, it is preferable to use approximately 10 to 500 parts bymass of the SAP with respect to 100 parts by mass of the fluff pulp. Inthis case, the SAP may be evenly mixed in each of the fluff pulp mats ormay be placed in layers between a plurality of fluff pulp layers.

It is preferable that the absorber is interposed between at least partsof the top sheet and the back sheet. Usually, the absorber is sandwichedbetween the top sheet and the back sheet, and the peripheral rim of theabsorber is sealed by adhesion so that the absorber is interposedbetween the top sheet and the back sheet. Therefore, the flap portions,in which the absorber is not interposed between the top sheet and theback sheet, are formed around the peripheral rim of the absorber.

It is preferable the entire absorber is wrapped by a hydrophilic sheet.This structure provides an advantage in that the SAP is prevented fromleaking from the absorber and that the absorber is provided with theshape stability.

There is no particular restriction on the shape of the absorber. Theshape of the absorber includes the shapes used in the conventionaldisposable diaper and other absorbent products, such as a rectangularshape, an hourglass shape, a calabash shape, and a T-shape, for example.

[1-4]. The top sheet: The top sheet is a sheet disposed to cover theupper surface of the absorber (i.e., the surface at the side of the skinof the wearer when the diaper is applied to the wearer). The top sheetis at least partially (i.e., a part or the entirety of the top sheet is)made of a liquid permeable material due to the need to cause theabsorber disposed at the side of the lower surface of the top sheet toabsorb the urine of the wearer.

The liquid permeable material forming the top sheet includes a wovenfabric, a nonwoven fabric, and a porous film, for example. Inparticular, it is preferable to use a hydrophilicized nonwoven fabricmade of a thermoplastic resin such as polypropylene, polyethylene,polyester, or nylon.

The top sheet may be formed by a single sheet material. Alternatively,the top sheet may be formed by a plurality of sheet materials. Forexample, in a frequently used embodiment of a tape-type diaper laterdescribed, a top sheet (i.e., a center sheet) made of a liquid permeablematerial is disposed at the center of the diaper, and another top sheet(i.e., a side sheet) made of a water repellent material is disposed atside flap portions of the diaper.

[1-5] The back sheet: The back sheet is a sheet disposed to cover thelower surface of the absorber (i.e., the surface at the side of theclothes of the wearer when the diaper is applied to the wearer). Theback sheet is made of a liquid impermeable material due to the need toprevent the urine of the wearer from leaking to the outside of thediaper.

The liquid impermeable material forming the back sheet includes, forexample, a liquid impermeable film made of a resin such as polyethylene.In particular, it is preferable to use a microporous polyethylene film.The microporous polyethylene film is formed with a multitude of microholes of a size of 0.1 to a few micrometers. The microporouspolyethylene film is liquid impermeable but moisture permeable, and thushas an advantage of capable of preventing the inside of the diaper frombecoming stuffy.

A sheet member (i.e., a cover sheet) may be pasted to the outer surfaceof the back sheet. The cover sheet is used to reinforce the back sheetand to improve the hand feeling (i.e., the tactile feeling) of the backsheet.

The material forming the cover sheet includes a woven fabric and anonwoven fabric, for example. In particular, it is preferable to use adry or wet nonwoven fabric made of a thermoplastic resin such aspolyethylene, polypropylene, or polyester.

[1-6] The absorbent member: In the two-piece-type and pants-type diaper,the top sheet, the back sheet, and the absorber are formed as onemember, i.e., the “absorbent member” having the absorbing and retainingfunction, and the absorbent member is joined with the exterior coveringmember, which has been manufactured separately from the absorbentmember. Thereby, the disposable diaper is formed. In the absorbentmember, as in the case of a sanitary napkin or the like, the top sheetand the back sheet are disposed on the upper surface and the lowersurface of the absorber, respectively, so that the absorber isinterposed between the top sheet and the back sheet. For example, thedisposable diaper 1 illustrated in FIG. 3 is an example in which theabsorbent member 14 is formed by inserting the absorber 22 between thetop sheet 18 and the back sheet 20 and adhering and sealing theperipheral rim of the absorber 22 to make the absorber 22 interposedbetween the top sheet 18 and the back sheet 20.

The absorbent member is formed into such a size to cover at least thecrotch part of the diaper. To ensure the leakage preventing effect,however, it is preferable to form the absorbent member into such a sizeto cover not only the crotch part but also a part of the front body partand the back body part. The absorbent member can be fixed to theexterior covering member with the hot-melt adhesive agent or the like,for example.

[1-7] The exterior covering member: The exterior covering member is amember having the fitting function of covering the body of the wearer.Specifically, the exterior covering member is a sheet-shaped member forforming respective parts of the front body part, the crotch part, andthe back body part.

In the two-piece-type and pants-type diaper, the absorbing and retainingfunction of absorbing and retaining the excrement of the wearer isperformed solely by the absorbent member, and thus there is no need touse the liquid impermeable material as the material forming the exteriorcovering member. The material forming the exterior covering memberincludes, for example, a nonwoven fabric formed by a synthetic fiber ofpolyethylene, polypropylene, polyester, or another thermoplastic resin.

The exterior covering member is fixed, with such members as theleg-surrounding stretchable members inserted in the exterior coveringmember. In many cases, therefore, the exterior covering member is formedby pasting together two or more nonwoven fabrics. For example, thedisposable diaper 1 illustrated in FIGS. 1 to 3 is an example in whichthe exterior covering member 16 is formed by two nonwoven fabrics, andleg-surrounding stretchable members 40, waist-surrounding stretchablemembers 42, and belly-surrounding stretchable members 44 are insertedand fixed between the two nonwoven fabrics.

[1-8] The respective stretchable members: In the pants-type disposablediaper, the leg-surrounding stretchable members and thewaist-surrounding stretchable members are generally provided, and it ispreferable to further provide the belly-surrounding stretchable members.

The leg-surrounding stretchable members are stretchable members placedalong the respective leg-surrounding openings. With the provision of theleg-surrounding stretchable members, highly stretchable gathers (i.e.,leg gathers) can be formed around the leg-surrounding openings.Accordingly, a clearance gap is not easily formed around the legs, andthe leakage of the urine from the leg-surrounding openings can beeffectively prevented.

The waist-surrounding stretchable members are stretchable members placedalong the waist-surrounding opening. With the provision of thewaist-surrounding stretchable members, a highly stretchable gather(i.e., a waist gather) can be formed around the waist-surroundingopening. With the waist gather, a clearance gap is not easily formedaround the waist, and the leakage of the urine from the area around thewaist can be prevented. Further, the fittedness of the diaper to thewearer is improved, and thus the diaper is prevented from slipping down.

The belly-surrounding stretchable members are stretchable members placedin a portion between the waist-surrounding opening and theleg-surrounding openings (i.e., a portion corresponding to the areaaround the belly of the wearer). With the provision of thebelly-surrounding stretchable members, a highly stretchable tummy gathercan be formed around the belly of the wearer. Coupled with the waistgather, the tummy gather can further improve the fittedness of thediaper and the effect of preventing the slide down of the diaper.

The disposable diaper 1 illustrated in FIGS. 1 and 2 is an example inwhich a plurality of the leg-surrounding stretchable members 40 areplaced around the peripheral rims of the leg-surrounding openings 12 aand 12 b, and a plurality of the waist-surrounding stretchable members42 are placed around the peripheral rim of the waist-surrounding opening10 so as to surround the waist-surrounding opening 10. Further, aplurality of the belly-surrounding stretchable members 44 are placed inthe portion between the waist-surrounding opening 10 and theleg-surrounding openings 12 a and 12 b (i.e., the portion correspondingto the area around the belly of the wearer) so as to surround the bellyof the wearer.

Each of these stretchable members can employ a similar structure to thestructure used in the opening stretchable member described above.Further, the material forming the stretchable member, the elongationrate of the material, the elongated state of the stretchable member whenthe stretchable member is fixed, and the like can be determined inconsideration of such factors as the extent of contraction of thegather.

[2] The manufacturing method: An embodiment of the method ofmanufacturing the disposable diaper according to the present inventionwill now be described, taking an example in which the disposable diaper1 illustrated in FIGS. 1 to 3 (i.e., the two-piece-type and pants-typediaper) is manufactured.

[2-1] The manufacture of the absorbent member: The absorber 22 wrappedby a hydrophilic sheet is disposed on the upper surface of the backsheet 20, and the top sheet 18 is disposed on the upper surface of theabsorber 22. Then, the peripheral rim of the absorber 22 is sealed byadhesion, sandwiched by the top sheet 18 and the back sheet 20. Thereby,the absorbent member 14 is obtained.

[2-2] The manufacture of the skin contact sheet: The upper sheet 24 a ispasted on the upper surface of the liner sheet 24 b, with the twoopening stretchable members 30 a and 30 b arranged in a predeterminedpattern. In this case, the two opening stretchable members 30 a and 30 bare arranged in such a pattern to cross at the point P between the stoolpassing opening 28 a and the urine passing opening 28 b, which are laterformed, and to surround a part of the peripheral rim of each of thestool passing opening 28 a and the urine passing opening 28 b.

Subsequently, the stool passing opening 28 a and the urine passingopening 28 b are formed into respective predetermined shapes on theliner sheet 24 b and the upper sheet 24 a, which have been pastedtogether. Thereby, the double-layer structured skin contact sheet 24 isobtained in which the two opening stretchable members 30 a and 30 b arearranged in such a pattern to cross at the point P between the stoolpassing opening 28 a and the urine passing opening 28 b, and to surrounda part of the peripheral rim of each of the stool passing opening 28 aand the urine passing opening 28 b.

[2-3] The manufacture of the standing gathers: One edge portion of thesheet member 32 a or 32 b is folded, and the two the standing gatherstretchable members 36 a and 36 b or 36 c and 36 d are tucked in andpasted to the obtained folded portion. Thereby, the standing gather 26 aor 26 b is obtained.

[2-4] The provision of the skin contact sheet and the like to theabsorbent member: The skin contact sheet 24 is pasted to a surface ofthe top sheet 18 which forms the absorbent member 14, and then each ofthe standing gathers 26 a and 26 b is pasted to the corresponding sideedge of the absorbent member 14 and the skin contact sheet 24, with eachof the standing gathers 26 a and 26 b tucking therein the correspondingside edge of the absorbent member 14 and the skin contact sheet 24.

[2-5] The manufacture of the exterior covering member: Two nonwovenfabrics for forming the exterior covering member 16 are first prepared.Then, the waist-surrounding stretchable members 42, thebelly-surrounding stretchable members 44, and the leg-surroundingstretchable members 40 are disposed and fixed by adhesion on the uppersurface of one of the nonwoven fabrics. Thereafter, the other one of thenonwoven fabrics is layered on and fixed to the upper surface of the oneof the nonwoven fabrics. Thereby, the exterior covering member 16 isobtained in which the waist-surrounding stretchable members 42, thebelly-surrounding stretchable members 44, and the leg-surroundingstretchable members 40 are interposed between the two nonwoven fabrics.

[2-6] The manufacture of the disposable diaper: The absorbent member 14is disposed at and fixed to the proximity of the crotch part of theexterior covering member 16. Then, the exterior covering member 16 isfolded in half such that the front body part 2 and the back body part 6are aligned with each other, with the absorbent member 14 on the insideof the folded exterior covering member 16. Thereafter, the front bodypart 2 and the back body part 6 are joined by such a method asheat-sealing, and the joining parts 8 are formed. Thereby, thedisposable diaper 1 illustrated in FIGS. 1 to 3 is manufactured.

The above-described sequence of processes can be continuously performedby a mechanical method or apparatus. For example, with a method orapparatus for continuously sending out a long sheet material or a longstretching material by a roller, for example, the continuous manufactureof the disposable diaper can be performed. This contributes to theimprovement of the productivity.

[3] The scope of application of the present invention: The scope ofapplication of the disposable diaper according to the present inventionis not limited to the above-described two-piece-type and pants-typediaper, but the present invention is also applicable to a one-piece-typeand pants-type diaper and a tape-type diaper, for example. That is,these diapers can also have the effects of the disposable diaperaccording to the present invention, if the skin contact sheet isdisposed above the surface of the top sheet and is formed with the stoolpassing opening of a predetermined shape.

The “one-piece-type diaper” refers to a type of diaper which includes atop sheet, a back sheet, and an absorber, similarly to thetwo-piece-type diaper, but in which the absorber having the absorbingand retaining function is interposed (i.e., embedded) between the topsheet and the back sheet and is integrated with the top sheet and/or theback sheet having the fitting function.

The “tape-type diaper” refers to a disposable diaper which includes atop sheet, a back sheet, an absorber interposed between at least partsof the two sheets, and tape fasteners for fitting the diaper, and inwhich a front body part and a back body part can be fixed to each otherby the tape fasteners. The “tape-type diaper” also includes the“one-piece-type” and the “two-piece-type,” and the disposable diaperaccording to the present invention is applicable to either type of thetape-type diaper.

The disposable diaper according to the present invention can bepreferably used as the diaper for an infant or an adult such as an elderor disabled person who needs nursing care. Further, in the disposablediaper according to the present invention, a discharged stool does noteasily directly contact with the skin of a wearer of the diaper.Accordingly, the disposable diaper according to the present inventioncan be preferably used particularly as the disposable diaper for aninfant who has a sensitive skin and thus frequently has skin trouble.

1. A disposable diaper comprising: an absorber; a top sheet disposed tocover an upper surface of the absorber and at least partially formed ofa liquid permeable material; and a back sheet disposed to cover a lowersurface of the absorber and formed of a liquid impermeable material;wherein the disposable diaper further includes a skin contact sheetdisposed above the top sheet and formed with a stool passing opening,which is an opening capable of passing a stool therethrough, and to theboth sides of the skin contact sheet, at least a pair of standinggathers which are leakage prevention walls capable ofthree-dimensionally standing is formed.
 2. The disposable diaperaccording to claim 1, wherein the standing gathers are formed withfolded parts of side edges of the skin contact sheet and integrallyformed with the skin contact sheet.
 3. The disposable diaper accordingto claim 1, wherein the standing gathers are formed along both sideedges of the skin contact sheet.
 4. The disposable diaper according toclaim 2, wherein the standing gathers are formed along both side edgesof the skin contact sheet.
 5. The disposable diaper according to claim1, wherein the standing gathers are formed that upper end edges of thestanding gathers are disposed to positions higher than a surface of theskin contact sheet.
 6. The disposable diaper according to claim 2,wherein the standing gathers are formed that upper end edges of thestanding gathers are disposed to positions higher than a surface of theskin contact sheet.
 7. The disposable diaper according to claim 3,wherein the standing gathers are formed that upper end edges of thestanding gathers are disposed to positions higher than a surface of theskin contact sheet.
 8. The disposable diaper according to claim 1,wherein the standing gathers' lower end edges are disposed on thesurface of the skin contact sheet.
 9. The disposable diaper according toclaim 3, wherein the standing gathers' lower end edges are disposed onthe surface of the skin contact sheet.
 10. The disposable diaperaccording to claim 4, wherein the standing gathers' lower end edges aredisposed on the surface of the skin contact sheet.